Inter-rater reliability of classification systems of scapular dyskinesis

Prevalence of scapular dyskinesis varies across records, with overhead athletes being more frequently affected than non-overhead athletes A number of methods have been described to evaluate scapular kinematics and scapular dyskinesis. The "yes/no" and the "4-type" classification systems are widely accepted and diffusely used among orthopaedics and physical therapists. The inter-rater reliability for both the "yes/no" and the "4-type" classification systems may be different. Moreover, differences between physical therapists and orthopaedic surgeons may exist. Seven examiners (2 orthopaedic surgeons and 5 physical therapists) were asked to evaluate a mixed sequence of video recordings of healthy subjects and patients affected by shoulder, scapular or clavicular disorders and to assess scapular dyskinesis using the "yes/no" and the "4-type" classification systems. Cohen's kappa coefficient (κ) and weighted kappa were used to measure inter-rater reliability. Twenty-four subjects were enrolled. In general, the "4- type" system has higher κ values than ''yes/no'' classification system and orthopaedic surgeons achieve higher reliability than physical therapists for both systems. The clinical evaluation of active shoulder movements permits reproducible assessment and classification of scapular dyskinesis, in particular for the "4-type" classification system. The "4-type" classification system can be used to assess and classify scapular dyskinesis, especially among orthopaedic surgeons.